Designing low-power video image stabilization IP for FPGAs

Image stabilization is an important capability for many electro-optic sensors, where an operator or user is required to view the output imagery. The technique can therefore enhance many practical viewing systems, spanning a very broad range of applications including those found in defense and security sectors.

Stabilization provides a means for reducing both image blur and unwanted frame-to-frame image shifts and rotations, thereby aiding image interpretation and reducing the operatorís workload. For those systems that require the operator to locate or classify features within the video stream (typically recognition and identification), then a stabilized image stream will help improve the accuracy of these tasks.

There are a number of techniques for stabilizing an image which are either based on mechanical correction or image processing. Mechanical stabilization techniques include those that gyroscopically stabilize the whole camera system or use elements within the camera to effectively move the lens or detector array.

Mechanical stabilization techniques are well-established, although they can have a limited rate of response. Furthermore, they tend to be more expensive, consume more power and are physically larger and heavier. Mechanical stabilization techniques used within the camera housing are generally less expensive and are physically more compact. However, they can have performance limitations such as an inability to correct for roll, and may operate over a restricted range of unwanted camera movements. In addition, such integrated camera techniques are less well-established for infrared cameras and those cameras that use interchangeable lenses. Finally, it should be noted that mechanical stabilization corrects for movement associated with the camera, but does not correct for other effects such as atmospheric scintillation.

Figure 1: Unstabilized image set. The 5 frames have been false-colored and superimposed to illustrate the movement effect.